Electrostatic pick-up device



Get 7, 1930.

w. D. CROZIER ELECTROSTATIC PICK-UP DEVICE Filed Sept. 4, 1928 Patented Oct. 7, 1930 UNITED "STATES PATENT OFFICE.-

WILLIAM D. CROZIER, OF GENEVA, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, T0

UNITED REPRODUCERS PATENTS CORPORATION, OF ST. CHARLES, ILLINOIS, A. GOR- PORATION OI NEVADA ELECTROSTATIC PICK-U]? DEVICE Application filed September a, 1928. Serial No. 303,721.

The present invention relates to electrostatic or condenser type of pick-up devices, such as those used for talking machines and phonographs and like sound reproducing devices, and with an electrical amplifying device. Among the objects of the invention is to provide a novel pick-up device of the condenser or electro-static type, and one which will convert impressed mechanical vibrations from a record into electrical energies in consonance .with the undulations of the record so as to reproduce sound with ample volume and a faithfulness not peculiar to the usual type of electromagnetic type of pick-up device. The converted energies are'preferably impressed 'upon the grid of an audion tube in an amplifying circuit.

Other objects,'advan tages, capabilities and features are comprehended by'the invention as will later a pear and as are inherently possessed thereby.

Referring 'to the drawings, Fig. 1 shows in a diagrammatic way an embodiment ofthe invention; and Fig. 2 is a diagrammatic showing of the amplifying circui Ivieferring more. particularly to the drawings, the embodiment selectedto illustrate the invention is shown in relation to a talk ing machine or phonograph record 1 having undulated grooves for operating a stylus 2 carried in a stylus holder 3 and suitably vsecured therein by any suitable means, such as athumb screw 4. The stylus holder is carried by the end of a bar 5 having a fulcrum 6 on a fixed part 7 of thedevice. The bar has an upper end 8 to which may be secured,

as by soldering an end of a. thin flat metal piece 9. This piece may be of thin fiat steel, and is designed to'be stiiilohgitudi nally, but adaptedfto have slight flexibility V transversely, so as to compensate for the are movement of thelend 8 of the bar 5 when the same is ,being vibrated or oscillated by the record grooves. v

The other end of the part or element 9 may also be soldered or otherwise secured to two or more struts of light weight stiff wires 10 and 11 which lead to'and are suitably secured, as by soldering, to the marginal portions of a conducting member 12 of the electro-static pickup device. This member may be of metal and is made of convex form and may also be hollow in order that itmay be verylight in weight. The convex side of this member 12 is presented to and is in contact with a thin dielectric sheet or diaphragm 13 held at its margins in fixed parts 14 and 15 of the device. As an example of a dielectric used, rubberized silk or the like may be used It is to be understood that the invention is not limited thereto, but may comprehend other dielectric materials, such as parchments, paper, sheet rubber and other like and similar materials. It is preferable that this dielectric be flexible. On the of the dielectric as shown.

The convexity of the surface of the member 12 is such as to provide therebetween a thin divergent air space such that when the member 12 is vibrated and the diaphragm 13 with the conducting surface 16 made to flex, the radially successive points, from the center point of contact on the surface of the member 12 will'progressively come into the greater proximity, with the flexible dielectric. In this way, progressive parts of the member 12 will come closer and closer to the.

opposite side of the dielectric, is provided a surface ofthe dielectric 13 and thus increase the electro-static stress existingbetween the conducting member and the dielectric. The conducting-part 16 is connected by a wire or conductor 18 and the bar 5 is connected by another wire 19 preferably at a point 20 close to the fulcrum 6. These wires are in the circuit shown in Fig. 2.

- Referring to Fig. 2, the amplifying circuit shown as an example, comprises an amplifying tube 20 of the audion type and comprising a plate 21 connected by conductor 22 to an output terminal 23. The circuit continues to an output terminal 24, through a battery 25, conductor 26 connected to one side '27 of the filament circuit of the filament is a usual B battery used in such circuits.

conductor 29, it being understood that there is a. heating source across the conductors 27 and 29 for heating the filament. The tube also has a grid 31 connected by a con= ductor 32 leading to a condenser 33 and thence by a conductor 18 or 19'to the electrostatic device A shown in detail in Fig. 1 of the drawings. From this leads the conductor 19 or 18 to the filament conductor 27.

Also, in shunt, may also be connected resistances 34 and 35 and batteries 36 and 37, as shown in the diagram of Fig. 2. The value of these resistances, batteries and condensers may be that suitable to obtain the best results from the circuit. As an example, the condenser 33 may be of-about one tenth of a microfarad.

The resistance 34 and 35 are preferably of high resistance of at least one megohm and as high as twenty megohms. Battery 36 is preferably of a high voltage battery of about one hundred volts or more. Battery 37 may be of the usual C biasing type of battery to suit the value of the tube used. Battery 215 tmay be replaced by any device for obtaining electrical current from a supply circuit. The capacity of the electro-static device A may be but a few micro-microfarads.

In operation, the record will cause the bar 5, by the way of stylus 2, to vibrate and this vibration will be transmitted to the longitudinally stiff member 9 and through the stiff wires or struts 10 and 11 to the metal member 12. Thiswillcausethemetalmember to press more or less against the dielectric 13 and cause the same to flex in proportion therewith. The coating 16 will also flex with the dielectric. This vibration will cause the electrostatic stresses to vary in proportion tothe vibrations set up, and the impressed electrical energies will pass through the-circuit and be impressed upon the grid 31 as also upon the plate 21. It is to be understood that although one stage of amplification is shown in Fig. 2 that other stages may be added in accordance with the usual circuit.

As the member 12 is vibrated, points located 'ment of the invention, it is to be understood that the invention is not limited thereto, but may comprehend other constructions, arrangements of parts, details, and features without departing from the spirit thereof.

Having thus disclosed the invention, I claim:

1. An electrostatic pick-up device comprising a flexible dielectric member having a conducting surface, a movable conducting member associated with the opposite surface of said dielectric member, andmeans associated with the conducting member to move it in accordance with the undulations of a record.

2. An electrostatic pickup device comprising a flexible dielectric member having a conducting surface, a movable conducting memher having a curved surface proximate to the opposite surface of said dielectric member, and means associated with the conducting member to move it in accordance with the undulations of a record.

3. An electrostatic pick-up device comprising a flexible dielectric member having a conducting surface, a movable conducting memher having a convex surface adjacent the opposite surface of said dielectric member, and means associated with the conducting member to move it in accordance with the undulations of a record.

4. An electrostatic pick-up device comprising a thin flexible diaphragm of dielectric material, a flexible metal coating on one of the surfaces of the diaphragm, a metal member contacting the other of said surfaces of the diaphragm, and means to vibrate said mem ber and flex said diaphragm in accordance with a sound record.

5. An electrostatic pick-up device comprising a thin flexible diaphragm of dielectric material, a flexible metal coating on one of the surfaces of the diaphragm, ametal memher having a convex surface contacting the other of said surfaces of the diaphragm, and means to vibrate said member and flex said diaphragm in accordance with a sound record.

6. In an electrostatic pick-up device provided with a flexible dielectric member having conduct ng surface, a conducting member adapted to contact the non-conducting surface of the dielectric, astylus operated memher, and a thin element connecting said stylus operated member and said conductin element for transmitting vibratory movement to said conducting member, said element being stifl' in its direction of movement transmission and flexible in a transverse direction.

7. In an electrostatic pick-up device provided with a flexible dielectric member having a conducting surface, a conducting member adapted to contact the non-conducting surface of the dielectric, said conducting member comprising a convex element adapted to present its convexity to said dielectric, and a strut connected to said element and to a stylus operated means.

8. In an electrostatic pick-up device provided with a flexible dielectric member having a conducting surface, a conducting member adapted to contact the non-conducting surface of the dielectric, said conducting member comprising a convex element adapted to, present its convexity to said dielectric, a strut having an, end rigid with said element, a movement transmitting part connected to the other end of the strut and tea stylus opa thin fiat metal part connected to the other end of the strut and to a stylus operated means.

10. An electrostatic pick-up device com prising a pair of conducting elements and a thin dielectric therebetween, one of said conducting elements being movable, and means operated by a sound record and connected to 7 said movableconducting element to vibrate the same, said dielectric and the other of said conducting elements being flexible.

In witness whereof, I hereunto'subscribe my name to this specification.

WILLIAM D. CROZIER. 

